Production of nitrogen-halogen compounds



United States Patent 3,506,401 PRODUCTION OF NITROGEN-HALOGEN COMPOUNDSMervin D. Marshall, Fombell, Pa., assignor to Mine Safety ApplianceCompany, Pittsburgh, Pa., a corporation of Pennsylvania No Drawing.Filed July 7, 1960, Ser. No. 41,443 Int. Cl. C01c 1/00 US. Cl. 23-205 4Claims This invention relates to a method of producing certain compoundsin which halogen atoms are combined with nitrogen, and more particularlyto the production of chlorodifluoramine, ClNF and dinitrogentetrafluoride, N F

The compounds to which this invention relates are relatively newproducts in which halogen atoms are bonded to nitrogen. These compoundsare reactive and are excellent intermediates and oxidizing agents. Forexample, dinitrogen tetrafluoride, N F is effectively used as anoxidizer in rocket and similar type engines where it is used inconjunction with conventional fuels such as hydrazine. In suchapplications the dinitrogen tetrafiuoride takes the place of and is usedin the same manner as the well known oxidizer ClF and other similaroxidizers. Dinitrogen tetrafiuoride also can be used to produce otheroxidizers, such as, for example, the new compound NF ClO which is madeby reacting N F with nitronium perchlorate, as disclosed in thecopending application Ser. No. 41,445 of Mervin D. Marshall and Leon L.Lewis filed on even date herewith.

chlorodifluoramine, CINF is also an excellent and quite reactiveintermediate and can be used to make, for example,1-chloro-2-difluoraminoethane by reacting it with ethylene. Moreover,chlorodifluoramine is a good additive for use in conjunction with thoseoxidizers now employed in rocket engines. Thus, it can be added tohydrogen peroxide to impart properties to that oxidizer which areassociated with fluorine, whereby the mixture has more desirableproperties than does the hydrogen peroxide alone. The mixture is usedjust as is the hydrogen peroxide.

The process of my invention, in its'broad aspect, comprises the reactionof chlorine with difluoramine. This reaction produces a mixture ofdinitrogen tetrafluoride and chlorodifluoramine, with the proportion ofeach product varying with the conditions and procedures used, as will bedescribed hereinafter.

The temperature at which the reaction is carried out is not of criticalimport. Generally room temperature or below is used, and quite lowtemperatures, i.e;, down below 100 C., have been used with success.Higher temperatures can also be used, although it is best to avoid veryhigh temperatures if chlorodifluoramine is the desired product, becausechlorodifluoramine tends to decompose to dinitrogen tetrafluoride atelevated temperatures. l a a As stated above, the reaction ofdifluoramine with chlorine invariably'produces a mixture of products.However, I have found that the proportion of these products can begreatly varied by using different ratios of reactants and by controllingthe conditions under which the reaction is carried out. The mostimportant variable in determining the product which is obtained is theratio of chlorine to difluoramine used in the starting materials for theprocess. I have found that high chlorine to difluoramine mol ratiosfavor the formation of chlorodifluoroamine; a ratio of C1 to HNF of overabout 2:1 is necessary to produce any substantial amount ofchlorodifluoramine. At ratios of chlorine to difluoramine below about 2:1, the predominant product is N F I have also found that mixing favorsthe production of chlorodifluoramine. That is, the better the reactantsare mixed during the reaction period, the higher the yield ofchlorodifluoramine which is obtained. In this connection, Leon L. Lewisand I, in accordance with our copending application Ser. No. 380,091filed July 2, 1964, have discovered that the use of a solvent fordifluoramine, such as carbon tetrachloride, diethyl ether and benzene,aids in the production of chlorodifluoramine.

In one example of the method and practice of my invention, 8.4 mols ofdifiuoroamine and 12 mols of chlorine were condensed together in areaction vessel and allowed to react at room temperature (about 25 C.)for several hours. The products were then separated by fractionalcondensation and analyzed by mass spectrometer and infra-red analysis.It was found that 2.2 mols of dinitrogen tetrafiuoride had been producedduring the reaction, with only a small amount of chlorodifluoraminebeing obtained.

Lewis and I, in another test in which a solvent was used to carry outthe reaction, added 0.94 mol of difluoramine to 5.07 mols of chlorine incarbon tetrachloride. The mixture was stirred for two and one-half hoursat room temperature and then the volatile products were removed andseparated by fractional condensation. Analysis of the product showedthat almost a quantitative yield of chlorodifluoramine had beenproduced, with only a trace of dinitrogen tetrafluoride being obtained.

The effect of varying the ratios of the reactants was studied in stillother tests which were carried out in accordance with the examples andthe method described above. The reuslts of several of these tests areset forth below in Table I.

TABLE L-MOL RATIOS Reactants, Cl /HNF Products, ClNF /N F It may benoted that, while in all cases both products were obtained to someextent, an equimolar ratio of reactants produced almost excusivelydinitrogen tetrafluoride, whereas mol ratios of chlorine to difiouramineabove about 2:1 resulted in the product being predominatelychlorodifluoramine.

According to the provisions of the patent statutes, I have. explainedthe principle and mode of practicing my invention and have describedwhat I now consider to be its best embodiments. However, I desire tohave it understood that, within the scope of the appended claims, theinvention may be practiced otherwise than as specifically described.

I claim:

1. A method of producing dinitrogen tetrafiuoride, N F andchlorodifluoramine, CINF which comprises reacting chlorine withdifluoramine, HNF and recovering the chlorodifluoramine and dinitrogentetrafluoride thus produced.

2. A method of producing dinitrogen tetrafiuoride which comprisesreacting chlorine with difluoramine in a molar ratio of chlorine todifluoramine of less than about 2:1, and recovering the dinitrogentetrafluoride thus produced.

3. A method of producing chlorodifluoramine which comprises reactingchlorine with difluoramine in a molar ratio of chlorine todifluoramineof at least about 2:1 and recovering the chlorodifluoramine thusproduced.

4. A process for the preparation ofchlorodifluoramine CARL D. QUARFORTH,Primary Examiner which comprises reacting difluoramine with chlorine. MJ MCGREAL Assistant Examiner References Cited Hoffman et al., Chem.Reviews, vol. 62, pp. 1 to 7 5 23356, 367 (1962).

U.S. Cl. X.R.

1. A METHOD OF PRODUCING DINITROGEN TETRAFLUORIDE, N2F4, ANDCHLORODIFLUORAMINE, CINF2, WHICH COMPRISES REACTING CHLORINE WITHDIFLUORAMINE, HNF2, AND RECOVERING THE CHLORODIFLUORAMINE AND DINITROGENAND TETRAFLUORIDE THUS PRODUCED.